Sinking shafts and boreholes



July 19, 1927 w. G. MINUTH SINKING SHAFTS AND BOREHOLES Filed March 18. 1925 Patented I July 19, 1927.

UNITED STATES WILHELM G. IINUTE, CELLE, GERMANY.

'SINKING SHARES AND BOBEHOLES.

Application filed March 18, 1925, Serial No. 16,342, and in Germany August 18, 1924.

My invention refers to the art of sinking shafts and bore holes down to the greatest depths, more especially through quicksand. It is a particular object of my invention to provide means whereby the sinking of shafts and bore holes can be effected in a cheaper and more convenient manner than was hitherto possible.

According to the practice hitherto adopted in the great majority of cases the drill or jet of water used for excavating the soil or rock is made to work in the hollow of a tubbing extending below ground andwhich was allowed to be lowered in the bore hole by its own weight or under pressure applied from above in proportion as the excavation ef-.

wall of the fected by the drill or the like proceeded. On a certain depth being reached, which in many cases did not exceed about 20 metres, the tubbing would stick fast in the surrounding rock and would not sink down further. This necessitated the introduction into the tubbing of another tubbing the external diameter of which was-less than the internal diameter of the first tubbing and which now started descending along with the drill or the like. After a further 40 metres the sec- 0nd tubbing would stick fast also and a third tubbing of still inferior diameter had to be inserted'and so on. Obviously owing to the high costs of the tubbings this mode of proceeding is very expensive. Apart therefrom the gradual decrease in the diameter of the tubular space enclosin the drill prevented the use of larger dri ls and the 0btention of bore holes of large diameter.

According to the present invention the sticking fast of the first tubbing is effectively prevented by inserting between the outer wall of the tubbing and the rock a liquid or viscous layer of annular diameter which not only separates the tubbing from the rock, thereby preventing it from adhering, but owing to its pressure exerted on the inner pit or bore hole effectively prevents the'caving in of rock or sand and the breaking in of water, gas, petroleum orthe like which may be present in the rock. I prefer using a liquid or viscous mass having a, higher specific gravity than water, and in many cases I have found it useful to employ a clay suspension or slime such as has already been used as a packing for loose rock and for layers containing water, gas and petroleum.

I will now proceed to describe my invention more particularly with reference to a device embodying same and which can be used with advantage for carrying my invention into effect.

In the. drawings aflixed to this specification and forming part thereof, such device is illustrated diagrammatically by way of example.

In the drawings,

Fig. 1 is a longitudinal section of the device in operative position in a bore hole, I

Fig. 2 is a similar view of part of the lower portion of the device and Fig. 3 is a cross section on the line 3-3 in Fig. 2, drawn to a larger scale.

- eferring to the drawings, 5 is the tub hing inserted in the bore hole and 6 is a sealing tube sharpened at its lower edge and mounted on the lower end of the tubbing. This tube should have a length of about 5 meters, but shorter and longer tubes can be used with advantage in certain cases. The

inner diameter of the tube 6 is about equal to the inner diameter of the tubbing 5, but

the outer diameter is considerably greater,

exceeding the outer diameter of the tubbing for instance by 50 to 70 mms. Obviously, when the tube 6 is lowered into the rock following the excavation produced by the drill 8. or other boring means, its outer diameter will predetermine the inner diameter of the bore hole. The outer diameter of the tubbing 5 bein considerabl smaller, an annu lar space wi 1 be formed etween the tubbing 5 and the inner wall of the bore hole, and the tubbing will therefore be prevented altogether from coming in contact with the bore hole wall. In order, however, to prevent the rock from cavin in or water, gases or oil from breaking into this annular space, I

keep the space filled with a stationary liquid or viscous body, having preferably a higher specific gravity than water. 4

Obviously the great length of the sealing tube 6 enables it to work after the manner of a piston, and to revent the liquid or viscgus packing from finding its way below the s 0e.

Before starting the boring 0 eration I prefer sinking a pit 1 having a dzapth of a few metres. This pit is lined in some suitable manner and through an opening in the center of the bottom lining-'2 thereis sunk into the rock a short tube 3, the inner diameter of which is equal to the diameter of the bore hole. The'upper screw-threaded end 4 of the tube preferably projects somewhat above the bottom lining 2 of the pit. Through the tube 3 the drill 8 and the sealing tube 6 are introduced and in proportion as the boring operation proceeds,the tubbing is lengthened.

The pit 1 and the annular space 7 between the tubbing 5 and the wall of the bore hole are filled with a mass having a higher specific gravity than water, such as for instance a slime formed of a watery suspension of clay, The shaft 1 serves as a reservoir for permanently keeping the space 7 filled with a stationary column of the slime. Inasmuch as owing to this arrangement a'sticking fast of the tubbing in the bore hole cannot take place, all friction between the tnbbing and the bore hole being excluded, a single tubbing of constant diameter can be used down to the greatest depth.

In case" that at greater depths the li uid filling the annular space 7 above the sea ing tube 6 should become too viscous, l have provided means whereby it can at any moment be diluted with water through the shoe. To this end the tube 6 is mounted in the lower end of the tubbing for angular motion within certain limits which are predetermined by a stop or stops 11 projecting into a corresponding notch or notches 12 in the lower end of the tubbing. Channels 9 and 10 extending across the sealing tube 6 and the tubbing respectively can be made to register by turning the tubbing in the tube until the stop 11 meets the lateral wall of the notch 12. If water is now introduced into the tubbing it will escape through the channels 10, 9 and will dilute from below the column of slime 7. In a similar manner the entire column of slime can be replaced from below by pure water or by a slime of higher specific gravity.v This latter step will prove necessary for instance where the bore hole meets a spring or natural gas. In such cases the tube 3 can further be lengthened so as to project above ground or it can be packed by means of a stuffing box, and slime or the like can be forced into the annular space between the bore hole wall and the tubbing by means of a forcing pump, until the necessary pressure acting on the bore hole walls is ob tained.

The long sealing tube 6 further allows taking precautionary measures in case that eruptive rocks are met with, inasmuch as the long tube always precedes the column of liquid by several metres. The great length of the tube further warrants an exactly rectilinear boring. It can be extracted at any time for the purpose of sharpening it without any danger of rock caving in, rovided only that the bore hole be filled with slime or other liquid.

The novel process here described is particularly adapted for use with percussion I or rotation boring, wherein a 'current of water is sent down through the tubbing, because in this way large samples of rock will continuously be raised to the surface.

After the boringoperation has come to an end, I can either extract the tubbing and sealing tube or I can replace the liquid column 7 by a filling of concrete or the like.

I wish it to be understood that I do not desire to be limited to the particular character and sequence of operations or to the particular details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim l. The method of sinking bore holes, pits, shafts and the like comprising boring into the rock, subdividing the bore hole thus obtained into a central space of cylindrical cross section and an outer space of annular cross section and forming in said outer space a stationary body of a non-solid mass.

2. The method. of sinking bore holes, pits, shafts and the like comprising boring into the rock, subdividing the bore hole thus ob tained into a central space of cylindrical cross section and an outer space of annular cross section and keeping said outer space filled with a stationary body of a substantially liquid mass; I

3. The method of sinking bore holes, pits, shafts and the like comprising boring into the rock, subdividing the bore hole thus obtained into a central space of cylindrical cross section and an outer space of annular cross section and keeping said outer space filled with 9,3, stationary body of a non-solid mass of higher specific gravity than water.

a. The method of sinking bore holes, pits, shafts and the like comprlsing boring into the rock, subdividing the bore hole thus obtained into a central space of cylindrical cross section and an outer space of annular cross section and keeping said outer space filled with a stationary body of a watery suspension of clay.

5. The method of sinking bore holes, pits, shafts and the like comprising boring into the rock, subdividing the bore hole thus obtained into a central space of cylindrical cross section and an outer space of annular cross section, keeping said outer space filled with a stationary body of a non-solid mass and varying the physical properties of said mass.

6. The method of sinking bore holes, pits, shafts and the like comprism producing an excavation several metres in epth, lowering into the rock a short tube from the bottom of this excavation, boring into the rock through this tube, lowering into the bore hole thus produced a sealing tube and a tub bing of considerably smaller diameter fitted to said tube and keeping said excavation and the end of said tubbing,

the space between said tubbing and the bore hole filled with a stationary body of a liquid.

7 Apparatus for sinking bore holes, pits, shafts and the like comprising excavating means, a tubbing ofeven diameter surrounding. said excavating means, a sealing tube at the outer diameter of said sealing tube being considerably greater than the diameter of said tubbing and atleast equal to the diameter of said excavating means and means for establishing from above ground communication between the interior of said sealing tube and the space surrounding said tubbing.

8. Apparatus for sinking bore holes, pits, shafts and the like comprising excavating means, a tubbing surrounding said excavating means and a sealing tube of considerably greater diameter at the end of said tubbing, said sealing tube and tubbing having channels capable of being brought to register and of controlling the passage of liquid from the interior to the exterior of said tube and a stop on one of the parts limiting their relative angular movement. a

In testimony whereof I aifix my signature.

WILHELM G. MIN UTH. 

